MATH 431 Midterm: 2014 Math 431 - Anderson - Spring Exam 2
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This may earn you partial credit: no calculators or other electronic devices, please. Turn o your phone: you do not have to carry out complicated numerical computations, but you should simplify your answer if it is possible with reasonable e ort, please present your solutions in a clear manner. A numerical answer without expla- nation cannot get credit. Make all of the following computations. (a) (4 pts. ) Find p{x 3}. (you do not need to provide a decimal representa- tion. ) (b) (4 pts. ) Compute e[x 1] using the de nition of the expectation (i. e. do *not* use the fact that you may have memorized the desired expectation). (c) (4 pts. ) Let x have density function f (x) = 8x 9 for x 1 and zero otherwise. Suppose that e[x] = 5 and var(x) = 2. 3: (15 pts) let x be exp( 1.
